A single‐phase seven‐level buck‐boost common ground transformerless inverter for grid‐connected photovoltaic system

Abstract

Transformerless inverters have recently gained attention in view of their economic benefits and compactness for photovoltaic (PV) systems. However, the limited voltage regulation and common‐mode (CM) leakage current are major concerns in conventional transformerless PV inverters. This paper presents a single‐phase seven‐level buck‐boost common ground transformerless inverter (SLB2CGTLI) to achieve a wide range of output voltages and zero leakage current without any additional stages, respectively. The proposed converter utilizes switched capacitor (SC) cell to buck‐boost the input DC voltage and generates seven‐level voltage at the output terminals. A simple reconfiguration strategy is adopted in the switched capacitor cell to maintain the charge‐second balance across the capacitors. Moreover, the common ground between the AC grid neutral and the PV panel's negative terminal mitigates the leakage current completely. The theoretical steady state analysis for both buck and boost mode is presented and verified with simulation using MATLAB Simulink. The performance of the proposed inverter is analyzed and validated with experimental results by developing a laboratory prototype. Further, the dynamic response of the proposed converter is carried out using OP4510 real‐time simulator for the grid‐connected PV application.